/**
* Run a query -- includes checking for and running a Command.
* @return points to ns if exhaust mode. 0=normal mode
* @locks the db mutex for reading (and potentially for writing temporarily to create a new db).
* @asserts on scan and order memory exhaustion and other cases.
*/
string runQuery(Message& m, QueryMessage& q, CurOp& curop, Message &result) {
shared_ptr<ParsedQuery> pq_shared( new ParsedQuery(q) );
ParsedQuery& pq( *pq_shared );
BSONObj jsobj = q.query;
int queryOptions = q.queryOptions;
const char *ns = q.ns;
uassert( 16332 , "can't have an empty ns" , ns[0] );
if( logLevel >= 2 )
log() << "runQuery called " << ns << " " << jsobj << endl;
curop.debug().ns = ns;
curop.debug().ntoreturn = pq.getNumToReturn();
curop.debug().query = jsobj;
curop.setQuery(jsobj);
uassert( 16256, str::stream() << "Invalid ns [" << ns << "]", NamespaceString::isValid(ns) );
// Run a command.
if ( pq.couldBeCommand() ) {
curop.markCommand();
BufBuilder bb;
bb.skip(sizeof(QueryResult));
BSONObjBuilder cmdResBuf;
if ( runCommands(ns, jsobj, curop, bb, cmdResBuf, false, queryOptions) ) {
curop.debug().iscommand = true;
curop.debug().query = jsobj;
auto_ptr< QueryResult > qr;
qr.reset( (QueryResult *) bb.buf() );
bb.decouple();
qr->setResultFlagsToOk();
qr->len = bb.len();
curop.debug().responseLength = bb.len();
qr->setOperation(opReply);
qr->cursorId = 0;
qr->startingFrom = 0;
qr->nReturned = 1;
result.setData( qr.release(), true );
}
else {
uasserted(13530, "bad or malformed command request?");
}
return "";
}
const bool explain = pq.isExplain();
const bool tailable = pq.hasOption(QueryOption_CursorTailable);
BSONObj order = pq.getOrder();
BSONObj query = pq.getFilter();
/* The ElemIter will not be happy if this isn't really an object. So throw exception
here when that is true.
(Which may indicate bad data from client.)
*/
if ( query.objsize() == 0 ) {
out() << "Bad query object?\n jsobj:";
out() << jsobj.toString() << "\n query:";
out() << query.toString() << endl;
uassert( 10110 , "bad query object", false);
}
// Tailable cursors need to read newly written entries from the tail
// of the collection. They manually arbitrate with the collection over
// what data is readable and when, so we choose read uncommited isolation.
OpSettings settings;
settings.setQueryCursorMode(DEFAULT_LOCK_CURSOR);
settings.setBulkFetch(true);
settings.setCappedAppendPK(pq.hasOption(QueryOption_AddHiddenPK));
cc().setOpSettings(settings);
// If our caller has a transaction, it's multi-statement.
const bool inMultiStatementTxn = cc().hasTxn();
if (tailable) {
// Because it's easier to disable this. It shouldn't be happening in a normal system.
uassert(16812, "May not perform a tailable query in a multi-statement transaction.",
!inMultiStatementTxn);
}
// Begin a read-only, snapshot transaction under normal circumstances.
// If the cursor is tailable, we need to be able to read uncommitted data.
const int txnFlags = (tailable ? DB_READ_UNCOMMITTED : DB_TXN_SNAPSHOT) | DB_TXN_READ_ONLY;
LOCK_REASON(lockReason, "query");
Client::ReadContext ctx(ns, lockReason);
scoped_ptr<Client::Transaction> transaction(!inMultiStatementTxn ?
new Client::Transaction(txnFlags) : NULL);
bool hasRetried = false;
while ( 1 ) {
try {
replVerifyReadsOk(&pq);
// Fast-path for primary key queries.
if (!explain && !tailable) {
replVerifyReadsOk(&pq);
if (_tryQueryByPKHack(ns, query, pq, curop, result)) {
if (transaction) {
transaction->commit();
}
return "";
}
}
// sanity check the query and projection
if (pq.getFields() != NULL) {
pq.getFields()->validateQuery( query );
}
if (tailable) {
Collection *cl = getCollection( ns );
if (cl != NULL && !(cl->isCapped() || str::equals(ns, rsoplog))) {
uasserted( 13051, "tailable cursor requested on non-capped, non-oplog collection" );
}
const BSONObj nat1 = BSON( "$natural" << 1 );
if ( order.isEmpty() ) {
order = nat1;
} else {
uassert( 13052, "only {$natural:1} order allowed for tailable cursor", order == nat1 );
}
}
// Run a regular query.
// these now may stored in a ClientCursor or somewhere else,
// so make sure we use a real copy
jsobj = jsobj.getOwned();
query = query.getOwned();
order = order.getOwned();
const ConfigVersion shardingVersionAtStart = shardingState.getVersion( ns );
const bool getCachedExplainPlan = ! hasRetried && explain && ! pq.hasIndexSpecifier();
const bool savedCursor = queryWithQueryOptimizer( queryOptions, ns, jsobj, curop, query,
order, pq_shared, shardingVersionAtStart,
getCachedExplainPlan, inMultiStatementTxn,
result );
// Did not save the cursor, so we can commit the transaction now if it exists.
if (transaction && !savedCursor) {
transaction->commit();
}
return curop.debug().exhaust ? ns : "";
}
catch ( const QueryRetryException & ) {
// In some cases the query may be retried if there is an in memory sort size assertion.
verify( ! hasRetried );
hasRetried = true;
}
}
}
/**
* Run a query -- includes checking for and running a Command.
* @return points to ns if exhaust mode. 0=normal mode
* @locks the db mutex for reading (and potentially for writing temporarily to create a new db).
* @yields the db mutex periodically after acquiring it.
* @asserts on scan and order memory exhaustion and other cases.
*/
const char *runQuery(Message& m, QueryMessage& q, CurOp& curop, Message &result) {
shared_ptr<ParsedQuery> pq_shared( new ParsedQuery(q) );
ParsedQuery& pq( *pq_shared );
BSONObj jsobj = q.query;
int queryOptions = q.queryOptions;
const char *ns = q.ns;
if( logLevel >= 2 )
log() << "runQuery called " << ns << " " << jsobj << endl;
curop.debug().ns = ns;
curop.debug().ntoreturn = pq.getNumToReturn();
curop.debug().query = jsobj;
curop.setQuery(jsobj);
// Run a command.
if ( pq.couldBeCommand() ) {
BufBuilder bb;
bb.skip(sizeof(QueryResult));
BSONObjBuilder cmdResBuf;
if ( runCommands(ns, jsobj, curop, bb, cmdResBuf, false, queryOptions) ) {
curop.debug().iscommand = true;
curop.debug().query = jsobj;
curop.markCommand();
auto_ptr< QueryResult > qr;
qr.reset( (QueryResult *) bb.buf() );
bb.decouple();
qr->setResultFlagsToOk();
qr->len = bb.len();
curop.debug().responseLength = bb.len();
qr->setOperation(opReply);
qr->cursorId = 0;
qr->startingFrom = 0;
qr->nReturned = 1;
result.setData( qr.release(), true );
}
else {
uasserted(13530, "bad or malformed command request?");
}
return 0;
}
bool explain = pq.isExplain();
BSONObj order = pq.getOrder();
BSONObj query = pq.getFilter();
/* The ElemIter will not be happy if this isn't really an object. So throw exception
here when that is true.
(Which may indicate bad data from client.)
*/
if ( query.objsize() == 0 ) {
out() << "Bad query object?\n jsobj:";
out() << jsobj.toString() << "\n query:";
out() << query.toString() << endl;
uassert( 10110 , "bad query object", false);
}
Client::ReadContext ctx( ns , dbpath ); // read locks
const ConfigVersion shardingVersionAtStart = shardingState.getVersion( ns );
replVerifyReadsOk(&pq);
if ( pq.hasOption( QueryOption_CursorTailable ) ) {
NamespaceDetails *d = nsdetails( ns );
uassert( 13051, "tailable cursor requested on non capped collection", d && d->isCapped() );
const BSONObj nat1 = BSON( "$natural" << 1 );
if ( order.isEmpty() ) {
order = nat1;
}
else {
uassert( 13052, "only {$natural:1} order allowed for tailable cursor", order == nat1 );
}
}
// Run a simple id query.
if ( ! (explain || pq.showDiskLoc()) && isSimpleIdQuery( query ) && !pq.hasOption( QueryOption_CursorTailable ) ) {
int n = 0;
bool nsFound = false;
bool indexFound = false;
BSONObj resObject;
Client& c = cc();
bool found = Helpers::findById( c, ns , query , resObject , &nsFound , &indexFound );
if ( nsFound == false || indexFound == true ) {
if ( shardingState.needShardChunkManager( ns ) ) {
ShardChunkManagerPtr m = shardingState.getShardChunkManager( ns );
if ( m && ! m->belongsToMe( resObject ) ) {
// I have something this _id
// but it doesn't belong to me
// so return nothing
resObject = BSONObj();
found = false;
}
}
BufBuilder bb(sizeof(QueryResult)+resObject.objsize()+32);
bb.skip(sizeof(QueryResult));
curop.debug().idhack = true;
if ( found ) {
n = 1;
fillQueryResultFromObj( bb , pq.getFields() , resObject );
}
auto_ptr< QueryResult > qr;
qr.reset( (QueryResult *) bb.buf() );
bb.decouple();
qr->setResultFlagsToOk();
qr->len = bb.len();
curop.debug().responseLength = bb.len();
qr->setOperation(opReply);
qr->cursorId = 0;
qr->startingFrom = 0;
qr->nReturned = n;
result.setData( qr.release(), true );
return NULL;
}
}
// Run a regular query.
BSONObj oldPlan;
if ( explain && ! pq.hasIndexSpecifier() ) {
MultiPlanScanner mps( ns, query, order );
if ( mps.usingCachedPlan() ) {
oldPlan =
mps.oldExplain().firstElement().embeddedObject()
.firstElement().embeddedObject().getOwned();
}
}
// In some cases the query may be retried if there is an in memory sort size assertion.
for( int retry = 0; retry < 2; ++retry ) {
try {
return queryWithQueryOptimizer( m, queryOptions, ns, jsobj, curop, query, order,
pq_shared, oldPlan, shardingVersionAtStart, result );
} catch ( const QueryRetryException & ) {
verify( retry == 0 );
}
}
verify( false );
return 0;
}
